Means for adjusting variable condensers



Feb. 1l, 1930. w. BAECKLER MEANS FOR-ADJUSTING VARIABLE CONDENSERS Filed Jan. 22, 1929 ATTORNEYS NVENTOR I Wax/1, M,

Patented Feb. 11, 1930 nl'rnn sin BAECKLER, 017' LAKEWOOD, OHIO, ASSIGNOR T0 NATONAL CARBON COMPANY INC., A CORPORATION OF NEW 'YRK Ennns non nna'nsniira Application tiled January 29, 1929. Serial No.

This 'invention pertains to variable condensers adaptedv for tuning the circuits of radio receivers and more speciically to a means for matching the capacities ot a gang ot such condensers at Various positions Within their range.

ln a multi-stage radio frequency amplier, employing one Variable ain condenser for tuning each stage, it is common practice to mechanically connect the several condensers so the stages may be simultaneously tuned by the operation 'of a single condenser control. Forthe proper functioning ,ot sn'oh an ampliier, itis essential that each stage be tuned to substantially the same frequency, as an amlitier is non-selective and insensitive if the requenoies to which the successive stages are tuned are not Very nearly identical. To fuliill this requirement, it is essential that the several condensers in the uni-control system7 or gang, have identical capacities in all positions, or, to use a vterm Well known in the art, the condensers must track.' Not only must they match at a given frequency, say 1000 kilocycles, but the rate of capacity change during the movement oi the tuning control must be the same for all7 so that, being matched at 1000 kilocycles, they will also be matched-at 600 lrilocyoles, or any other frequency Within the' range ci the amplifier. lt is very difficult to commercially manufacture such a gang of Variable condensers so their capacities inateh throughout their range, and considerable economy is effected it wider tolerancesV are allowed in the manufacture and assembly, the insulting differences eliminated by snbseqient adinetot the individual r units so they track with the themagnitude oli determined solely by the particular unit ander Theretore, obgeet to provide a ineens to n tiesogf rions points r/it they are neef to frequency empl L 1.1,. l match ti t VARIABLE CNDENSERS able air conciensers at the time oi' manufacture, so the capacity of each throughout its range is substantially the saine as that of another condenser adopted as a standard. Other aims, objects, and novel features will be apparent fromA the drawing and the iol lowing description.

'lhe objects of this invention are attained by the mechanism shown inthe accompanyinndrawing, in which:

Fig. 1 is a plan View oa gang of condensers embodying this invention. y

Fig. 2 is a'ti'ansverse View alongthe line Qe-Qof Fig. 1 looking in the direction oi the arrows.

3 is the saine View as that of 2 showing the movable plates of the condenser in various adjusted positions.

Fig. is a schematic diagram of a circuit adapted for being tuned by one or more of the condensers i' the shown in Fig. l

Fig. 5 is an enlarged View of two forms the partially detached portions shown at in Figs. 2 and 3, and

Fig. 6 is a sectional View along the line -6 of Fig. 5 looking in the direction oil arrows.

rlhe invention may be appied to a gane condensers such as that shown in Fig. 1 c ,prising a frame 10 hayii" compartments n 11 12, 13 and 1li- With one et four condensers 15, 16, 17 and 18 in each coin artment. -Each or" the four condensers '15. 1 17 and 1S may have a pluiality oi connected stator plates densei's in unison. lhe ;nr 16. 1'? and 18 are con in so far as it is c llhen cont.

condensers 15, exactly alike le. its of a radio the condensers 3 'i fangecl to tane tube of one o its respective i by condenser gram 'Fig'. e.

l ous adjusted A three stage radio frequency amplifier and antenna input system, tuned by four condensers such as those shown in Fig. 1 is well known in the art and it is understood that the gang of condensers may comprise any plural num-l ber as the invention about to be described is' Anot limited to a 'gang'comprising the particular number shown. Furthermore, the gang of condensers may be dierent from that shown,

as this invention may be applied to two or more variable air condensers operated in uni'- son regardless of their arrangement. In order to adjust the capacities of the condensers 15, 16, 17 and 18, so they match throughout their range I provide one of the erably portions of the end plate that are partially punched out but leftso they will remain in place during shipment and use, but may be readily removed witha suitable instrument when the condensers are adjusted. These partially detached portions may be punched out entirely and then pressed back in place where they are held by the friction of the-surrounding metal as shown at 27 in Figs. 5 and 6, or they may be only partially punched out and left with a portion 28 of the metal 26 unsevered. One side of each ofthe partially detached portions 27 may be removed to provide an opening 30 in whlch the end of a pointed instrument may be inserted to pry them out of the plate 26, or one side of each of the partially detached portions 27 may be turned up to form an ear 31 under which. the end of a pointed instrument may be inserted to pry them out of the plate. It is understood, of course, that these partially detachedportions maybe of a form differentv from those shown.

The partially detached-portions 27 may be formed in and distributed throughout y the end plate of each of the condensersin a variety of sizes, shapes, and patterns, but satisfactory results may be secured when they are arranged as shown in Figs. 2 and 3. In condensers such as those illustrated the end plates arerotor plates and the partially detached portions 27 are formed in these plates so they may be easily reached and removed, but they may be formed in any of the plates of either the rotor or stator.

The rotor 22 ofthe condenser in Fig. 3 is shown in four positions, a, b, c, and d. These four positions represent positions of the rotors of condensers 15, 16, 17, and 18, at which their capacities may be adjusted to identical values. These four positions are selected for the purpose of illustration as, actually, the

. ers 15, 16, 17, and 18, so they match throughout their range, the rotors of thecondensers may first be set at position a. In .this position only the portion or area e of the rotor plates are meshed with the stator plates, and it is this portion e of the -rotor plates that controls the capacity of each of the condensers. Each of the four condensers is now examined or tested by a method well known in the art to determine its relative capacity. For example we will suppose that condenser 15 is found to have a slightly higher capacity than that of the other three 16, 17, and 18, which we assume to be substantially alike at this setting. To reduce the capacity of condenser 15 to that of the others, one or more of the partially detached portions 27 inthe area e of the end plate of condenser 15 is removed.

The rotor plates of the four condensers may then/be moved to position b. In this position an additional portion or area f of the rotor plates is meshed with the stator plates. In

this position the relative capacity of each of the four condensers is tested and, for example, we Will suppose that the capacity of condenser 16 is found to-be higher than that of the other condensers. To reduce the capacity of condenser 16 to that of the others, one or more of the artially detached portions 27 in the area f ofpthe'end plate of condenser 16 is removed. l

The rotor plates of the four condensers may then be moved to position c. In this position 'an additional portion or area g' of the rotor plates is meshed with the stator plates. In

this position the relative capacit of each of' the four condensers'is tested an for example, we will suppose that the capacity of condenser 17 is found to'be higher than that of the others. To reduce the capacity of condenser 17 to that of the others, one or more of the partially detached portions 27 in the area g of the end plate of condenser 17 is removed.

- The rotor plates of the four 'condensersmay then be moved to position d. In this position an additional portion or area L of the rotor plates is meshed with the stator plates. V In this positionthe relative capacity of each of the four condensers is tested and, for example, we will suppose that the capacity of condenser 18 is found to be higher than that of the others. To reduce the capacity of condenser 18 to that of the others, one or more of the partially detached portions 27 in the area 7L o the end plate of condenser 18 is removed'.

When the condensers are' in position a it is obvious that' the onl partially detached portions 27 that`may he their capacity are those in area e. When the removed to alter aia/raam condensers are moved to position only the partially detached portions 27 in area f should be removed to alter their capacity, because, if any of the portions 27 are removed from area e the capacity of the condensers will not match when moved back to' position a. Likewise, when the condensers are in position c the partially detached portions 27 should be removed from the area g only, as any removed from areas e and f would spoil the match or adjustment of the condensers when their rotors were moved back to positions a or When adjusting the condensers it is understood, of course, that the partially detached portions 27 may be removed from one or more of the condensers at any position as required to reduce the capacity of any number of high capacity condensers to that of one or more condensers having a lower capacity, as the invention is not limited to reducing the capacity of one condenser to that of several others in the method just described or purpose of illustration.

Condensers such as those described herein may also be adjusted to match a standard condenser. rlhis adjustment may be made during the course of manufacture, thereby economically producing more accurate condensers that may subsequently be assembled in gangs with the assurance that they will match, or track. The method of adjusting the capacity of single condensers to that ot a standard condenser may be the same as the method described herein for adjusting the. capacity of one condenser to that ot another in the same gang.

Various alterations and adaptations may be made in the `construction and arrangement of the apparatus shown and described herein without departing from the invention or sacrificing any o the rights thereunder.

ll claim: v

l. A variable condenser in which at least one of the plates thereof has a plurality of partially-detached portions of which certain ones may be removed to reduce the capacity of said condenser so it substantially matches that of another operated in unison therewith at various adjusted positions within the range of both.

2. A gang of variable condensers 1n which at least one of the plates of each condenser has a plurality of partially-detached portions of which certain ones may be removed to reduce the capacity of one or more of said condensers to substantially that of another of said condensers at various adjusted positions within the range of said condensers.

3. A gang of variable condensers in which at least one of the plates of each condenser` y has a plurality of partially-detached punchings of which certain ones may be removed to adjust the capacity of one or more of said condensers to that of another of said coudensers at one or more positions within the range of said condensers.

4. A gang of variable condensers in which at least one of the movable plates of each condenser has a plurality of partially-detached punchings of which certain ones may be removed to adjust the capacity of one or more of said condensers to that of another of said condensers at one or more positions within the range of said condensers.

5. A variable'air condenser having a plate with partially-detached portions therein of which certain ones may be removed to adjust the capacity of said condenser so it is substantially identical with that of a standard condenser throughout its range.

In testimony whereof, l ax my signature.

WALTER BAECKLER. 

